Grinding is a precision finishing process for improving the surface finish, size, and shape of the part with very tight tolerances.  Often required in medical and food processing to reduce the possibility of areas for microbes or bacteria to grow, it completes parts in fluid applications such as nozzles, injectors, or fittings ensuring smooth flow of the liquid or gas.

A typical range of Average Surface Roughness (Ra) of 8-16 µ (micron) inches can be achieved through a grinding process.  To see the surface difference in this roughness range you would need a microscope; however, your sense of touch of a part with this finish feels very smooth. Dimensionally grinding provides control of dimensions of +/- 0.0001 inches, and the geometric shape of the part concentricity, runout, or cylindricity within 0.0002 inches.  This is finer in size than the diameter of human hair.  These tight tolerances are typically specified for precision assembly of parts or precision control of flow through a nozzle.

MacFab’s finishing capability includes two different methods:

  • Surface grinding for precision flat plats
  • Inner Diameter (ID) honing, on the ID of a hole completed in Sunnen honing machines.

Surface Grinding


Imagine placing two iPad minis short edge to short edge. This is the envelope which your part can fit into our machines for grinding. Applications utilizing surface grinding – testing platforms, qualify surface for precision machining, or plates mounting in an assembly requiring tight tolerances dimensions or geometrically for flatness and parallelism.

Inner Diameter Honing


Our machine can hone a hole the diameter of the lead in a pencil up to the inside of a coffee can and just over a foot long. Honing is a slow grinding process thereby not inducing significant heat to the workpiece helping to maintain geometric shape and dimensions.

Materials Commonly Honed

  • Alloy Steel such as 4140
  • Heat Treated steels
  • Stainless Steel such as PH 17-4
  • Heat Treated Stainless Steel

While other manufacturers may outsource grinding to a third party, our vertical integration allows us to delivery you improved cost, quality, and lead times on parts requiring a grinding operation to complete.